Are you using a larger front sprocket?
The steering stem is kind of short on this bike, I imagine the Duke dimention is longer as the top clamp is raised.
My bike came with a liscence plate hanger to be installed presumably if one wanted to register it in a state that was not super fussy or paid not a lot of attention to the not for highway use stuff on the certificate of origion. It is supposed to have necessary wireing less the blinker relay if I recall. Headlight is pretty dim and those green charge lights are way too bright, I put a folded up paper towel over them when riding after dark. Even still it goes slow so good I have rode off road after dark.
Is that a Duke swingarm? Years ago I bought some street tires, metzler marathon, for a 500 two cycle single I had a plate on. I might mount them some day with a different front sprocket when I replace the chain just for fun. Part of the beauty of this bike is the brake levers on the handlebars, pulling equally hard in off road terrain, not sure how this will play out with the Duke front end.
I am pretty sure they had a sort of super moto variant for some of the European market. all I have had to replace is the headlight bulb.
I have been able to look at the parts diagrams wandering from here.
https://sparepartsfinder.ktm.com/I think the chasis parts for the most part can be found at bike bandit or similar for the gas bikes.
I think I asked my dealer if the side panels from the gasoline bikes would work, note missing on e/xc but did not get an answer.